Caption: Printing press. Historical artwork of men working in a 16th century printing press. The printing press (centre) is operated by a man turning a screw-threaded column, which presses the horizontal, inked plate down onto the paper. The sheets of paper are then hung out to allow the ink to dry before compiling them. Though previously known in China, European printing was independently invented by Johann Gutenberg in about 1450. The mass-production of cheap text greatly advanced the spread of knowledge. This image of a Scottish printing press is taken from a book published in 1526.